The primary objective of the project is to study the immunologic response of the rat gastrointestinal tract to antigenic stimulation, and, in this way, to help to provide a foundation for understanding how immune responses serve to maintain intestinal homeostasis and how these responses may relate to the pathogenesis of disease. Other goals are related to clinical problems and have included: 1. Characterization of the IgM rise seen following total or subtotal colectomy in patients with chronic inflammatory bowel disease. 2. To determine if secretory IgA, given orally in the form of human colostrum, will reverse the intestinal malabsorption sometimes associated with some immunologic deficiency syndromes. 3. Enumeration of proportions and absolute numbers of peripheral blood thymus-derived (T) and bone marrow-derived (B) lymphocytes in patients with Crohn's disease and chronic nonspecific ulcerative colitis.